Here is the procedure I go through(I have been accused of being a little off).
1. Know the area that you are in. If possible seek out a restroom in a bank or upscale department store. Never, and I mean never enter a gas station or convenience store restroom, even for #1.
2. Upon opening main door to restroom, take in the scent. Be sure there are no offending odors. If there are, move on to a different restroom.
3. Perform visual inspection. With this, I look at the floors and sinks to assess the general upkeep of the restroom. If there are any other restroom patrons using the facilities, I go back out and wait for the restroom to clear. I need full concentration while using a stall, and I find their movements and noises very distracting.
4. Open each stall door using a paper towel as a barrier between my hand and the door. Mentally grade each stall and pick the winner.
5. Before entering the winning stall fully, extend my leg to flush the toilet. It doesn't matter if the water looks clean. I pre-flush anyway.
6. Line the seat, either with provided seat cover(double layer, of course) or double layer of toilet paper.
7. At this point, I am able to sit. I do my business as quickly and efficiently a possible.
8. Flush toilet(again with foot) and exit stall.
9. Wash hands in sink. Make sure to soap all the way up to the elbows.
10. Use a paper towel to open restroom door and exit.